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Table 2 Quantification of aromatic moieties (lignin, hydroxycinnamates, inter-unit bondages) by combination analysis of 13 C and HSQC NMR spectra of wheat straw isolated MSL and CEL

From: Effects of lignin modification on wheat straw cell wall deconstruction by Phanerochaete chrysosporium

Aromatic moieties σ CH(ppm) and assignments Control MSL Control CEL Eight weeks MSL Eight weeks CEL
Lignin aromatic units      
Syringyl (S) 103.9/6.7 (S2/6), 25.7 27.3 24.1 24.5
106.4/7.4 (S'2/6 with α oxidization)
Guaiacyl (G) 110.8/6.97 (G2) 41.2 39.3 41.6 39.8
115.0/6.94 (G5),118.9/6.81 (G6)
p-hydroxyphenyl (H) 127.7/7.21 (H2/6) 1.6 1.4 2.3 1.8
S/G ratio   0.63 0.69 0.58 0.61
Hydroxycinnamates      
p-benzoate (PB) 132.4/7.63 (PB2/6) 0.5 1.2 1.3 0.2
p-coumarate (pCA) 130.0/7.47 (pCA2/6),115.5/6.79 (pCA3/5) 5.4 5.5 3.0 3.1
144.74/7.47
Ferulate (FA) 110.9/7.32 (FA2), 122.5/7.15 (FA6) 0.6 6.4 0.4 4.5
p-coumarate/ferulate   9 0.86 7 0.68
Cinnamates/lignin and tricin   0.09 0.18 0.06 0.11
Lignin-ending group      
Cinnamyl aldehyde (X2) 153.5/7.62 (X2α), 126.2/6.78 (X2β) 0.1 ND ND ND
Cinnamyl alcohol (X1) 128.34/6.44 (X1α), 128.35/6.22 (X1β) 0.6 ND ND ND
Lignan      
Tricin (T) 104.04/7.30 (T 2′/6'), 104.65/7.03 (T3) 8.5 5.6 12 6.6
94.1/6.56 (T8), 98.8/6.22 (T6)
Inter-unit bondages      
α-OH/β-O-4 71.1/4.74 (Aα-G), 71.8/4.8 (Aα-S) 28.3 33.8 31.7 36.5
α-keto/β-O-4 82.7/5.1 (Aα-keto) 1.5 2.4 0.4 1.1
Total β-O-4   29.8 36.2 32.1 37.6
Phenylcoumaran (β-5) 85.9/5.5 (Bα), 53.0/3.4 (Bβ) 5.4 5.7 3.0 4.1
Pino/resinol (β-β') 84.8/4.7 (Cα), 53.5/3.1 (Cβ), 1.3 0.9 1.4 1.2
Dibenzodioxocin (D) 83.4/4.9 (Dα), 85.5/3.8 (Dβ) 0.3 2.0 0.7 2.5
Spirodienone (SD) 81.4/5.0 (SDα), 59.5/2.8 (SDβ) 0.4 ND ND ND
α,β-diaryl ether (F) 79.6/5.5 (Fα) 0.5 2.1 0.4 1.3
γ-ending groups      
γ-OH in X1 structure 62-58/3.8-3.0 2.0 1.5 1.2 0.9
Acylation on γ position 60.8-58.8/3.8-3.35 5.4 15.6 2.0 10.1